Atomic Vocabulary
This is the smallest unit of an element.
An atom.
This Greek philosopher first suggested that matter is made of atoms.
Democritus
Most of the mass of an atom is found here.
The nucleus
An atom with 17 protons is this element.
Chlorine
Electrons are important in chemical reactions because they do this.
Bond with other atoms.
This particle has a positive charge and is found in the nucleus.
a proton
This scientist proposed the solid sphere model of the atom.
John Dalton
The identity of an element is determined by this.
Number of Protons
If an atom has 17 protons and 17 electrons, the atom is this.
Neutral
Bohr’s model explained this about electrons.
Energy levels/orbits around the nucleus
This particle has no charge and is located in the nucleus.
A neutron
This scientist discovered the nucleus using the gold foil experiment.
Ernest Rutherford
If an atom gains or loses electrons it becomes this.
An ion
If an atom has 8 protons and 8 electrons, what element is it?
oxygen
Rutherford discovered that atoms have this small, dense center.
Nucleus
This is the region where electrons move around the nucleus.
Electron Cloud
This scientist explained that electrons move in energy levels around the nucleus.
Niels Bohr
This particle has a negative charge.
An electron
The most common magnesium isotope if it is 78.99% is this.
Mg-24
Most particles passed through the gold foil because atoms are mostly this.
Empty space
Atoms of the same element that have different numbers of neutrons are called this.
isotopes
This experiment helped scientists discover the nucleus and empty space in atoms.
Gold foil experiment
The number of protons in an atom is called this.
Atomic number
The total number of protons and neutrons together is called this.
Mass number
Explain why Rutherford concluded atoms are mostly empty space.
Because most alpha particles passed straight through the gold foil without hitting anything.